Ensure Client.close() has finished in __aexit__

This wraps the closing behavior in a task. Subsequent callers of
.close() now await that same close finishing rather than short
circuiting. This prevents a user-called close outside of __aexit__ from
not finishing before no longer having a running event loop.

discord/client.py

@@ -317,7 +317,7 @@ class Client:
         self._enable_debug_events: bool = options.pop('enable_debug_events', False)
         self._sync_presences: bool = options.pop('sync_presence', True)
         self._connection: ConnectionState = self._get_state(**options)
-        self._closed: bool = False
+        self._closing_task: Optional[asyncio.Task[None]] = None
         self._ready: asyncio.Event = MISSING
 
         if VoiceClient.warn_nacl:
@@ -334,7 +334,10 @@ class Client:
         exc_value: Optional[BaseException],
         traceback: Optional[TracebackType],
     ) -> None:
-        if not self.is_closed():
+        # This avoids double-calling a user-provided .close()
+        if self._closing_task:
+            await self._closing_task
+        else:
             await self.close()
 
     # Internals
@@ -969,27 +972,29 @@ class Client:
 
         Closes the connection to Discord.
         """
-        if self._closed:
-            return
+        if self._closing_task:
+            return await self._closing_task
 
-        self._closed = True
+        async def _close():
+            for voice in self.voice_clients:
+                try:
+                    await voice.disconnect(force=True)
+                except Exception:
+                    # If an error happens during disconnects, disregard it
+                    pass
 
-        for voice in self.voice_clients:
-            try:
-                await voice.disconnect(force=True)
-            except Exception:
-                # If an error happens during disconnects, disregard it
-                pass
+            if self.ws is not None and self.ws.open:
+                await self.ws.close(code=1000)
 
-        if self.ws is not None and self.ws.open:
-            await self.ws.close(code=1000)
+            await self.http.close()
 
-        await self.http.close()
+            if self._ready is not MISSING:
+                self._ready.clear()
 
-        if self._ready is not MISSING:
-            self._ready.clear()
+            self.loop = MISSING
 
-        self.loop = MISSING
+        self._closing_task = asyncio.create_task(_close())
+        await self._closing_task
 
     def clear(self) -> None:
         """Clears the internal state of the bot.
@@ -998,7 +1003,7 @@ class Client:
         and :meth:`is_ready` both return ``False`` along with the bot's internal
         cache cleared.
         """
-        self._closed = False
+        self._closing_task = None
         self._ready.clear()
         self._connection.clear(full=True)
         self.http.clear()
@@ -1114,7 +1119,7 @@ class Client:
 
     def is_closed(self) -> bool:
         """:class:`bool`: Indicates if the websocket connection is closed."""
-        return self._closed
+        return self._closing_task is not None
 
     @property
     def voice_client(self) -> Optional[VoiceProtocol]: